Move implementation from IterableBase to Iterable.

sdk/lib/collection/iterable.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart.collection;
 
 /**
  * This [Iterable] mixin implements all [Iterable] members except `iterator`.
  *
  * All other methods are implemented in terms of `iterator`.
@@ skipping 188 matching lines @@
 
   String toString() => IterableBase.iterableToShortString(this, '(', ')');
 }
 
 /**
  * Base class for implementing [Iterable].
  *
  * This class implements all methods of [Iterable] except [Iterable.iterator]
  * in terms of `iterator`.
  */
-abstract class IterableBase<E> implements Iterable<E> {
-  // TODO(lrn): Base this on IterableMixin if there ever becomes a way
-  // to combine const constructors and mixins.
+abstract class IterableBase<E> extends Iterable<E> {
   const IterableBase();
 
-  Iterable map(f(E element)) => new MappedIterable<E, dynamic>(this, f);
-
-  Iterable<E> where(bool f(E element)) => new WhereIterable<E>(this, f);
-
-  Iterable expand(Iterable f(E element)) =>
-      new ExpandIterable<E, dynamic>(this, f);
-
-  bool contains(Object element) {
-    for (E e in this) {
-      if (e == element) return true;
-    }
-    return false;
-  }
-
-  void forEach(void f(E element)) {
-    for (E element in this) f(element);
-  }
-
-  E reduce(E combine(E value, E element)) {
-    Iterator<E> iterator = this.iterator;
-    if (!iterator.moveNext()) {
-      throw IterableElementError.noElement();
-    }
-    E value = iterator.current;
-    while (iterator.moveNext()) {
-      value = combine(value, iterator.current);
-    }
-    return value;
-  }
-
-  dynamic fold(var initialValue,
-               dynamic combine(var previousValue, E element)) {
-    var value = initialValue;
-    for (E element in this) value = combine(value, element);
-    return value;
-  }
-
-  bool every(bool f(E element)) {
-    for (E element in this) {
-      if (!f(element)) return false;
-    }
-    return true;
-  }
-
-  String join([String separator = ""]) {
-    Iterator<E> iterator = this.iterator;
-    if (!iterator.moveNext()) return "";
-    StringBuffer buffer = new StringBuffer();
-    if (separator == null || separator == "") {
-      do {
-        buffer.write("${iterator.current}");
-      } while (iterator.moveNext());
-    } else {
-      buffer.write("${iterator.current}");
-      while (iterator.moveNext()) {
-        buffer.write(separator);
-        buffer.write("${iterator.current}");
-      }
-    }
-    return buffer.toString();
-  }
-
-  bool any(bool f(E element)) {
-    for (E element in this) {
-      if (f(element)) return true;
-    }
-    return false;
-  }
-
-  List<E> toList({ bool growable: true }) =>
-      new List<E>.from(this, growable: growable);
-
-  Set<E> toSet() => new Set<E>.from(this);
-
-  int get length {
-    assert(this is! EfficientLength);
-    int count = 0;
-    Iterator it = iterator;
-    while (it.moveNext()) {
-      count++;
-    }
-    return count;
-  }
-
-  bool get isEmpty => !iterator.moveNext();
-
-  bool get isNotEmpty => !isEmpty;
-
-  Iterable<E> take(int n) {
-    return new TakeIterable<E>(this, n);
-  }
-
-  Iterable<E> takeWhile(bool test(E value)) {
-    return new TakeWhileIterable<E>(this, test);
-  }
-
-  Iterable<E> skip(int n) {
-    return new SkipIterable<E>(this, n);
-  }
-
-  Iterable<E> skipWhile(bool test(E value)) {
-    return new SkipWhileIterable<E>(this, test);
-  }
-
-  E get first {
-    Iterator it = iterator;
-    if (!it.moveNext()) {
-      throw IterableElementError.noElement();
-    }
-    return it.current;
-  }
-
-  E get last {
-    Iterator it = iterator;
-    if (!it.moveNext()) {
-      throw IterableElementError.noElement();
-    }
-    E result;
-    do {
-      result = it.current;
-    } while(it.moveNext());
-    return result;
-  }
-
-  E get single {
-    Iterator it = iterator;
-    if (!it.moveNext()) throw IterableElementError.noElement();
-    E result = it.current;
-    if (it.moveNext()) throw IterableElementError.tooMany();
-    return result;
-  }
-
-  E firstWhere(bool test(E value), { E orElse() }) {
-    for (E element in this) {
-      if (test(element)) return element;
-    }
-    if (orElse != null) return orElse();
-    throw IterableElementError.noElement();
-  }
-
-  E lastWhere(bool test(E value), { E orElse() }) {
-    E result = null;
-    bool foundMatching = false;
-    for (E element in this) {
-      if (test(element)) {
-        result = element;
-        foundMatching = true;
-      }
-    }
-    if (foundMatching) return result;
-    if (orElse != null) return orElse();
-    throw IterableElementError.noElement();
-  }
-
-  E singleWhere(bool test(E value)) {
-    E result = null;
-    bool foundMatching = false;
-    for (E element in this) {
-      if (test(element)) {
-        if (foundMatching) {
-          throw IterableElementError.tooMany();
-        }
-        result = element;
-        foundMatching = true;
-      }
-    }
-    if (foundMatching) return result;
-    throw IterableElementError.noElement();
-  }
-
-  E elementAt(int index) {
-    if (index is! int) throw new ArgumentError.notNull("index");
-    RangeError.checkNotNegative(index, "index");
-    int elementIndex = 0;
-    for (E element in this) {
-      if (index == elementIndex) return element;
-      elementIndex++;
-    }
-    throw new RangeError.index(index, this, "index", null, elementIndex);
-  }
-
-  /**
-   * Returns a string representation of (some of) the elements of `this`.
-   *
-   * Elements are represented by their own `toString` results.
-   *
-   * The representation always contains the first three elements.
-   * If there are less than a hundred elements in the iterable, it also
-   * contains the last two elements.
-   *
-   * If the resulting string isn't above 80 characters, more elements are
-   * included from the start of the iterable.
-   *
-   * The conversion may omit calling `toString` on some elements if they
-   * are known to not occur in the output, and it may stop iterating after
-   * a hundred elements.
-   */
-  String toString() => iterableToShortString(this, '(', ')');
-
   /**
    * Convert an `Iterable` to a string like [IterableBase.toString].
    *
    * Allows using other delimiters than '(' and ')'.
    *
    * Handles circular references where converting one of the elements
    * to a string ends up converting [iterable] to a string again.
    */
   static String iterableToShortString(Iterable iterable,
                                       [String leftDelimiter = '(',
@@ skipping 40 matching lines @@
     _toStringVisiting.add(iterable);
     try {
       buffer.writeAll(iterable, ", ");
     } finally {
       assert(identical(_toStringVisiting.last, iterable));
       _toStringVisiting.removeLast();
     }
     buffer.write(rightDelimiter);
     return buffer.toString();
   }
+}
 
-  /** A set used to identify cyclic lists during toString() calls. */
-  static final List _toStringVisiting = [];
+/** A set used to identify cyclic lists during toString() calls. */
+final List _toStringVisiting = [];
 
-  /** Check if we are currently visiting `o` in a toString call. */
-  static bool _isToStringVisiting(Object o) {
-    for (int i = 0; i < _toStringVisiting.length; i++) {
-      if (identical(o, _toStringVisiting[i])) return true;
-    }
-    return false;
+/** Check if we are currently visiting `o` in a toString call. */
+bool _isToStringVisiting(Object o) {
+  for (int i = 0; i < _toStringVisiting.length; i++) {
+    if (identical(o, _toStringVisiting[i])) return true;
+  }
+  return false;
+}
+
+/**
+ * Convert elments of [iterable] to strings and store them in [parts].
+ */
+void _iterablePartsToStrings(Iterable iterable, List parts) {
+  /*
+   * This is the complicated part of [iterableToShortString].
+   * It is extracted as a separate function to avoid having too much code
+   * inside the try/finally.
+   */
+  /// Try to stay below this many characters.
+  const int LENGTH_LIMIT = 80;
+  /// Always at least this many elements at the start.
+  const int HEAD_COUNT = 3;
+  /// Always at least this many elements at the end.
+  const int TAIL_COUNT = 2;
+  /// Stop iterating after this many elements. Iterables can be infinite.
+  const int MAX_COUNT = 100;
+  // Per entry length overhead. It's for ", " for all after the first entry,
+  // and for "(" and ")" for the initial entry. By pure luck, that's the same
+  // number.
+  const int OVERHEAD = 2;
+  const int ELLIPSIS_SIZE = 3;  // "...".length.
+
+  int length = 0;
+  int count = 0;
+  Iterator it = iterable.iterator;
+  // Initial run of elements, at least HEAD_COUNT, and then continue until
+  // passing at most LENGTH_LIMIT characters.
+  while (length < LENGTH_LIMIT || count < HEAD_COUNT) {
+    if (!it.moveNext()) return;
+    String next = "${it.current}";
+    parts.add(next);
+    length += next.length + OVERHEAD;
+    count++;
   }
 
-  /**
-   * Convert elments of [iterable] to strings and store them in [parts].
-   */
-  static void _iterablePartsToStrings(Iterable iterable, List parts) {
-    /*
-     * This is the complicated part of [iterableToShortString].
-     * It is extracted as a separate function to avoid having too much code
-     * inside the try/finally.
-     */
-    /// Try to stay below this many characters.
-    const int LENGTH_LIMIT = 80;
-    /// Always at least this many elements at the start.
-    const int HEAD_COUNT = 3;
-    /// Always at least this many elements at the end.
-    const int TAIL_COUNT = 2;
-    /// Stop iterating after this many elements. Iterables can be infinite.
-    const int MAX_COUNT = 100;
-    // Per entry length overhead. It's for ", " for all after the first entry,
-    // and for "(" and ")" for the initial entry. By pure luck, that's the same
-    // number.
-    const int OVERHEAD = 2;
-    const int ELLIPSIS_SIZE = 3;  // "...".length.
+  String penultimateString;
+  String ultimateString;
 
-    int length = 0;
-    int count = 0;
-    Iterator it = iterable.iterator;
-    // Initial run of elements, at least HEAD_COUNT, and then continue until
-    // passing at most LENGTH_LIMIT characters.
-    while (length < LENGTH_LIMIT || count < HEAD_COUNT) {
-      if (!it.moveNext()) return;
-      String next = "${it.current}";
-      parts.add(next);
-      length += next.length + OVERHEAD;
+  // Find last two elements. One or more of them may already be in the
+  // parts array. Include their length in `length`.
+  var penultimate = null;
+  var ultimate = null;
+  if (!it.moveNext()) {
+    if (count <= HEAD_COUNT + TAIL_COUNT) return;
+    ultimateString = parts.removeLast();
+    penultimateString = parts.removeLast();
+  } else {
+    penultimate = it.current;
+    count++;
+    if (!it.moveNext()) {
+      if (count <= HEAD_COUNT + 1) {
+        parts.add("$penultimate");
+        return;
+      }
+      ultimateString = "$penultimate";
+      penultimateString = parts.removeLast();
+      length += ultimateString.length + OVERHEAD;
+    } else {
+      ultimate = it.current;
       count++;
-    }
+      // Then keep looping, keeping the last two elements in variables.
+      assert(count < MAX_COUNT);
+      while (it.moveNext()) {
+        penultimate = ultimate;
+        ultimate = it.current;
+        count++;
+        if (count > MAX_COUNT) {
+          // If we haven't found the end before MAX_COUNT, give up.
+          // This cannot happen in the code above because each entry
+          // increases length by at least two, so there is no way to
+          // visit more than ~40 elements before this loop.
 
-    String penultimateString;
-    String ultimateString;
-
-    // Find last two elements. One or more of them may already be in the
-    // parts array. Include their length in `length`.
-    var penultimate = null;
-    var ultimate = null;
-    if (!it.moveNext()) {
-      if (count <= HEAD_COUNT + TAIL_COUNT) return;
-      ultimateString = parts.removeLast();
-      penultimateString = parts.removeLast();
-    } else {
-      penultimate = it.current;
-      count++;
-      if (!it.moveNext()) {
-        if (count <= HEAD_COUNT + 1) {
-          parts.add("$penultimate");
+          // Remove any surplus elements until length, including ", ...)",
+          // is at most LENGTH_LIMIT.
+          while (length > LENGTH_LIMIT - ELLIPSIS_SIZE - OVERHEAD &&
+                 count > HEAD_COUNT) {
+            length -= parts.removeLast().length + OVERHEAD;
+            count--;
+          }
+          parts.add("...");
           return;
         }
-        ultimateString = "$penultimate";
-        penultimateString = parts.removeLast();
-        length += ultimateString.length + OVERHEAD;
-      } else {
-        ultimate = it.current;
-        count++;
-        // Then keep looping, keeping the last two elements in variables.
-        assert(count < MAX_COUNT);
-        while (it.moveNext()) {
-          penultimate = ultimate;
-          ultimate = it.current;
-          count++;
-          if (count > MAX_COUNT) {
-            // If we haven't found the end before MAX_COUNT, give up.
-            // This cannot happen in the code above because each entry
-            // increases length by at least two, so there is no way to
-            // visit more than ~40 elements before this loop.
+      }
+      penultimateString = "$penultimate";
+      ultimateString = "$ultimate";
+      length +=
+          ultimateString.length + penultimateString.length + 2 * OVERHEAD;
+    }
+  }
 
-            // Remove any surplus elements until length, including ", ...)",
-            // is at most LENGTH_LIMIT.
-            while (length > LENGTH_LIMIT - ELLIPSIS_SIZE - OVERHEAD &&
-                   count > HEAD_COUNT) {
-              length -= parts.removeLast().length + OVERHEAD;
-              count--;
-            }
-            parts.add("...");
-            return;
-          }
-        }
-        penultimateString = "$penultimate";
-        ultimateString = "$ultimate";
-        length +=
-            ultimateString.length + penultimateString.length + 2 * OVERHEAD;
-      }
-    }
+  // If there is a gap between the initial run and the last two,
+  // prepare to add an ellipsis.
+  String elision = null;
+  if (count > parts.length + TAIL_COUNT) {
+    elision = "...";
+    length += ELLIPSIS_SIZE + OVERHEAD;
+  }
 
-    // If there is a gap between the initial run and the last two,
-    // prepare to add an ellipsis.
-    String elision = null;
-    if (count > parts.length + TAIL_COUNT) {
+  // If the last two elements were very long, and we have more than
+  // HEAD_COUNT elements in the initial run, drop some to make room for
+  // the last two.
+  while (length > LENGTH_LIMIT && parts.length > HEAD_COUNT) {
+    length -= parts.removeLast().length + OVERHEAD;
+    if (elision == null) {
       elision = "...";
       length += ELLIPSIS_SIZE + OVERHEAD;
     }
-
-    // If the last two elements were very long, and we have more than
-    // HEAD_COUNT elements in the initial run, drop some to make room for
-    // the last two.
-    while (length > LENGTH_LIMIT && parts.length > HEAD_COUNT) {
-      length -= parts.removeLast().length + OVERHEAD;
-      if (elision == null) {
-        elision = "...";
-        length += ELLIPSIS_SIZE + OVERHEAD;
-      }
-    }
-    if (elision != null) {
-      parts.add(elision);
-    }
-    parts.add(penultimateString);
-    parts.add(ultimateString);
   }
+  if (elision != null) {
+    parts.add(elision);
+  }
+  parts.add(penultimateString);
+  parts.add(ultimateString);
 }